Apparatus for testing coatings



Nov. 14, 19.50 J. R. MARCUS 2,530,257

APPARATUS FOR TESTING COATINGS Filed Dec. 9, 1944 4 Shasta-Sheet 1 rusanec. 1944 4 Sheets-Sheet 2 S QN NN QN s .MA/ m .QW NN .\NN um .wn E RM?N 7%////// Mim .Q 1 nw Q k vill Il J. R. MARCUS APPARATUS FOR TESTINGCOATINGS Nov. 14, 1950 4 Sheets-Shut `4 Filed Dec. 9. 1944 Patented Nov.14,

UNITED vSTATES 1 PATENT omer:

' 2,530,251 Y. MZ..-

ern Electric Company, N. Y., a corporation of New York Incorporated, NewYork.

Anuncie neeembees, im, sel-m 116.501,40

(ci. vs -1s.)

schim. l

This invention relates .neat'h the beam. The beam is pivoted ioroscillation and carries a weight supporting carriage which maybe fedalong the beam. to change the lever arm thereof. by a motor driven screwdriving in synchronism with a driving screw for the carriage whichsupports the specimen whereby.V

after one of the probes has been selectively rendered operable, thelever arm oi the beam is. -gradually changed to apply a graduallyincreasing' weight to the probe engaging a test sample on -the carriageand simultaneously therewith the carriage is moved to drag the -testspecimen in the path oi the probe. A

control circuit is provided whereby the driving power for the motor isinterrupted when a probe breaks through the paint coating on the testspecimen, and the position oi the weight at the time that the motorcircuit is interrupted may be read upona scale scribed on the beam,thereby to force a probe through the paint coating.

' to apparatus for testing coatings and more particularly to anapparatus 2 in the direction of the arrows showing the specimensupporting carriage in end elevation;

llig.'lisanirregularverticalsectionalviewon an enlarged scale, takensubstantially along the linel-l oi Fig. 1 in the direction of thearrows, and showing the specimen supporting carriage and drive thereforin section;

Fig. 8 is a longitudinal sectional view on an enlarged scale. takensubstantially along the line l-j oi. Fig. 3 in the direction oi thearrows and showing' the detalls of the drive for the weight supportingcarriage and specimen supporting carriage;

Fig. 9 is an enlarged fragmentary side elevational view oi the beam andprobes and showing the structure whereby the probes may be alternatelyrendered Operable; and

Fig. 10 is a. fragmentary plan view taken substantially along the lineIll-l0 of Fig. 1 and showing, on anenlarged scale. a carriage forsupporting the test specimen, parts being broken away to'illustrate ameans whereby the test specimen supporting carriage may be shiftedtransversely oi the path oimovement of the carriage to dispose variousportions o! the test specimen to be acted upon by the probes.

In the drawings, the apparatus is illustrated as-'being mounted upon abase member l5, ou`

which there is mounted a brake releasing solenoid Il and a driving motorI1. In addition to supporting the brake releasing solenoid and drivingto indicate the amount oi pressure required to A complete understandingof the invention may be had by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings, wherein Fig. l is a side elevational view of an apparatus fortesting coatings made inaccordance with the present invention;

Fig. 2 is a circuit diagram illustrating the control cireuitschematically;

Fig. 3 is a plan view of the apparatus shown in Fig. l. part beingbroken away to conserve space;

Fig. 4 is a side elevational view oi the weight supporting carriagewhich travels along the beam, part oi the beam being broken away to moreclearly illustrate details oi the carriage;

Fig. 5 is a transverse vertical sectional view taken substantially alongthe line l-S of Fig. 4 in the direction oi.' the arrows showing detailsof construction oi the beam and weight supporting carriage;

Fig. 6 is an irregular vertical sectional view taken substantially alongthe line H o! Fig. 1

motor. the base I5 supports an inverted channel member I8. the uppersurface of which comprises a trackway for a specimen supportingcarriage, `designated generally by the numeral Il. Intermediate the endsof the inverted channel member I8, a pair of blocks 20 and 2| arepositioned' to serve as spacer members for bearing plates 22 and 23,respectively, which, together with the blocks 20 and 2|, are attached tothe inverted channel member il by means of machine screws 24-24. At theends oi' the channel member I8, upright members 25 and 28 are attachedthereto to serve as bearings for a pair oi drive screws 21 and 2ljournalled in anti-friction bearings in the upright members and adaptedto drive the specimen supporting-carriage l! and a weight supportingcarriage, indicated generally by the reference numeral 29, respectively.

The drive screws 21 and 28 have gears 20 and 3l ilxed to them andmeshing one with another. The gear 3l also meshes with an idler gear 32suitably mounted for free rotation on the upright member 25 and. inturn, meshing with an intermediate gear 33. The gear I3 is freelyrotatable with respect to the upright member 28 and has attached to it alarge driving gear 84, which, in turn, meshes with a spur gear 88 on thedrive shaft of the motor I1. Thus, when the motor |1 is actuated,rotation will be imparted through the gear train just described to drivethe drive screws 21 and 28 simultaneously. v

Formed integrally with or suitably attached to the gear 3| is atruste-conical brake drum 48 having a brake band 48 attached thereto forcngagement by the internal surfaces of a brake member 41 slidablyengaging the reduced end of the screw 28. The brake member 41 isprovided with a flange 48 and a head 48 and the iiange 48 is engaged bycompression springs 50-50 which surround posts 8I-5I mounted in theupright member 28 and are compressed between the ange 48 and lock nutassemblies 52-52 threaded onto. the posts 5|. Thus, the compressionsprings 80-88 urge the brake member 41 to engage the brake band 48 onthe drum 45. Attached to the head 48 of the brake member 41 is a bracket53 having a lever 54 pivoted thereto on a pin 85. The lever 54 carriesan adjustable abutment member 88, which engages a plate 51 attached tothe ends of the posts 8|. The lever 54 is pivotally connected to asolenoid core 58, which, upon actuation of the brake releasing solenoidI8, will be moved to the left,

as viewed in Figs. 1 and 8, to rock the lever 54:

clockwise and withdraw the` brake member 41 from engagement with thebrake band 48 whenever the motor I1 is operated, as will be describedmore in detail hereinafter.

Journalled for free oscillation in anti-friction bearings 85 positionedat the upper ends of the bearing plates 22 and 28 is a beam supportingyoke 66, to which a channel-shaped beam 81 may be suitably attached, forexample, by welding or bolting, the two members together. Thechannel-shaped beam 81, as shown most clearly in Figs. 6 and 7, has ahat surface 88 milled in it to a suilicient depth to provide a pair ofguide shoulders GSi- 88, which serve to guide the wheels 10-10 of theweight-supporting carriage 28. The weight-supporting carriage 28comprises a weight-supporting plate 1 I, from which there extend fourlegs 12-12, on each of which there is mounted one of the wheels 10. Thelegs 12-12 are spaced apart a distance sumcient to receive anirregularly shaped travelling nut 18, which threadedly engages the drivescrew 28 and extends transversely of the carriage 28 a suillcientdistance to engage the legs 12, whereby, when the drive screw 28 isrotated, the carriage 28 will move along the channel-shaped beam 81. Thetravelling nut 13 has an upwardly extending portion 14, which entersinto the channel of an inverted channel member 15 attached to andextending between the upright members and 28. This channel member servesto prevent rotation of the travelling nut 18 with respect to thecarriage 29 and prevents any torque being applied to the carriage 28which might tend to support the carriage and weights 18-18 mounted onthe weight-supporting plate 1|. v

Suitably attached to the under side of the beam 61, as shown mostclearly in Figs. 7 and 9,' are a pair of probe-supporting blocks 11 and11 having chuck members 18 and 18, respectively, formed integrally withthem. The chuck 18 has an aperture 80 formed in it for receiving a probemember 8|, which may be locked in place in the aperture 80 by means of aset screw 82. The probe member 8| is provided with a rounded point 88,which, when engaged with a coating of paint on the test specimen, willabrasively engage the coating and tend to scrape the coating from thetest specimen and thereby effect a scratch adhesion test on thespecimen. 'Ihe chuck 18 is provided with a probe receiving aperture 88,in which a probe member, designated generally by the numeral 84, may bepositioned. The probe member 84 is provided with a shank 88, in whichthere is formed a groove 88. The shank portion of the probe member 84extends into the aperture 88 a suiilcient distance so that a flatsurface of a knurled ilange 81 will engage a face of the chuck 18 andthe groove 88 will be in alignment with the nib of a set screw 88 havinga knurled head. Disposed eccentrically with respect to the shank 88 is aneedle-receiving portion 88 adapted to receive a needle 80, which isheld in the portion 88 by a thumb screw 8|. As shown in the variousilgures of the drawing, the needle is positioned to extend just belowthe rounded point 88 of the probe 8|. However, upon loosening the setscrew 88, the probe member 84 may be rotated to carry its eccentricportion to a higher position than that shown in the various figures andto thus move the needle 88 to a position where its point will be abovethe rounded point 88 of the probe 8| and then the probe 88 will engage atest panel to make the scratch adhesion test on ay coating on the testspecimen or panel. When the probe member 84 is in the position shown inthe various figures, a mar resistance test will be made on the testpanel. 'I'he probe may be disengaged from the test specimen by manuallymanipulating an eccentric 84 mounted on a shaft 88, which is journalledin the upright member 28 and is provided with a handle 88, whereby itmay be manipulated. yThe eccentric 84 is positioned below the end -ofthe beam 81 and may be manipulated to raise the beam and carry theprobes out of engagement with the specimen on the carriage I8.

In order to counterbalance the weight oi' the probes 8| and 84 and theirsupporting devices, a weight |82 is attached to the under side of thebeam 81 to the left of its bearings (Fig. 1). This weight has a bar |04attached to it for carrying a threaded support post |08, on which aweight |08 is threaded. The weight |88 is provided with a knurled locknut |01, whereby the weight may be rotated on the post |88 to adjust thebeam 81 and then locked in place so that it will exactly balance whenthe carriage 28 carrying the weights 18 is in the position shown in Fig.1, where a reference line |08 on the carriage is at the zero point of ascale |08 scribed on the beam 81. The scale |08 may be graduated toindicate the amount of pressure applied to the probes at the variouspositions of the carriage 28 along the beam 81.

'Ihe specimen-supporting carriage I8 is adapted to carry a test specimenin the form of a plate or sheet of metal IIII having a protectivecoating III, which is to be tested. The carriage |8 may be driven by atravelling nut ||2 resting on the upper face of the channel member I8and threadedly engaging the drive screw' 21. The nut |I2 has a pair ofprojections |I8I|8 on directly opposite edges thereof for entrance intoa series of slots |I4--I I4 formed in oppositely disposed portions ||8and I I8 of the carriage I8. The portions I|8 and I|8 are madeofinsulating material and each has two legs ||1 extending downwardlyfrom it to rotatably sup- .port wheels I|8| I8, which ride upon theupper surface ci the channel member I3. The portions III and lit aresuitably attached to a metallic bed |I3, which is adapted to receive thett specimen in the iorm of" the sheet of metal Iltwith the coating tobetested on its upper surface.

Mounted upon the bed I I3 are four pivot blocks |23-'-|24. which carrypivot pins |2| in position to einer an intermediate portion m or s slamp|23 for pivotalw supporting these. clamps in position to clamp Vthesheet of metal III having the coating III on it in position to betested. vThe lower tace oi' each oi the clamps |23 has a compressibieinsulating material cemented to it. for example, a strip of ielt |24,which will engage the coating II| on the sheet of metal III vto clampthe specimen on the bed III. At their lower ends, the clamps |23 areadapted to receive pivot members |24 and |23, which are freelyoscillatable in suitable apertures formed in the lower edge of the clamp|23. The pivotmember I2! engages a reduced portion oi' a rod |21 and isheld in place on the reduced portion of the rod |21 by a cap member IIIpinned to the rod |21. The pivot member |24 is internallythreaded tothreadedly engage a threaded portion |23'A o! the rod |21 and rotationmay be imparted to the rod |21 by a thumb nut |34 on a reduced squareshank I3I ofthe rod |21, which shank is threaded to receive a retainernut |32. When a test specimen in the 'form oi a metallic plate I|3 withs coating .l l l 'is placed upon meines m, u may be moved intoengagementwith an end member |33.'V which is attached to the bed II.whereby, upon movement of the carriage Il, the specimen will not bedragged away from the clamping members |23.,

,The control circuit for controlling the operation 'of the apparatusincludes a main power supply switch I44, which, when closed, willconnect current from a source I4I to the normally open contacts of arelay |42 and to the normally open contacts of a relay |43. The relay|42, upon energization. serves to supply power to the motor I1 to drivethe vmotor in one direction and the relay |43, upon energization, servesto supply currentA to drive the motor I1 in the opposite direction.'I'he motor I1 has a pair of leads |44, vwhich will maintain it inoperation in either direction, and has a pair of leads |44 connected toits. starting winding (not shown) for initiating the operation of themotor I1 in either of two directions, depending upon whether the relay|42 or |43 is operated. Initiation of operation oi' relay |42 may beeii'ected by closing a switch |43 to supply current through a normallyclosed switch |41 to the winding of relay |42 and, upon energization ofrelay |42. `the .relayl will lock operated over its locking contacts andthe normally closed contact of a relay |43, the normally closed contactoia. reversing switch |43, and the normally closed contacts of anemergency lstop switch |53. Relay |43 operates under control of anamplifier |53 connected to the source of current upon closure of theswitch |44 and operable under control oi whichever one of the probemembers 2| or 34 is in operative contact with the test specimen on thebed III of the specimensupporting carriage I3. The amplifier Ill isprovided to permit the usage of a low value current at the probes. whichis ampliiled in the ampliiier to operate relay I 43.

The probe'whlch is being used, upon breaking through the coating on thetest specimen. will complete a circuit from the ampliiier |43 through 5through the coating on the metallic sheet III.

it will complete a circuit through the ampliiler Ill to energize therelay |43 and break the locking circuit to relayy |42. The solenoid IIis connected in parallel with the motor I1 and. when m the motor I1 isdeenergized. the solenoid |l will also be deenergized. The circuit tothe coil ci relay |42, as pointed out hereinbefore. is com-` pletedthrough normally closed switch |41 andA this switch is mounted upon thechannel member is I3 in such position, as indicated in Fig. i. that thespecimen-supporting carriage I3 will open the switch |41 when thecarriage moves the test specimen to a position where the probes are ad-`iacent the right end of a specimen ,on the ear- 0 riage. The switch|44, in initiating the forward movement of the carriage I3, willcomplete a circuit 'through the normally closed contacts of switch I andnormally closed contacts ofthe emergency stop switch |53 and the circuit5 through the windings of relay |42 will be maintained by the contactsof relay |44.

,After a specimen has been tested by moving t it beneath`a probe, thecarriage I3 may be returned to its right hand position (Fig. l) by omanipulating reversing switch |43, which will break thev locking circuitfor relay |42 and momentarilymake a circuit to energize the winding ofrelay |43 over a circuit from the current source through a normallyclosed switch |54, the nor- 35 mally open and now closed contacts ofswitch i |43. stop switch |43 yand back to the current source. As soonas a relay |43 pulls up, it will remain locked up over a circuit fromthe current source through the stop switch |53, locking contacts ofrelay |43 and normally closed switch |44, back to the main currentsource at switch |44. This circuit will be maintained until the carriageI3 reaches its extreme right hand position (Fig. 1) where it willactuate the switch |54 a to open the locking circuit for relay |43 afterthe'carriage Il is moved from under the probes.

A more complete understanding of the invenftion may be had by referenceto the following brief description of the mode of operation of theapparatus. A test specimen. comprising a sheet .of metal I I0 having acoating I I thereon, may be placed upon the bed I It of the carriage I!and the carriage may then be placed on the travelling nut |I2 with theprojections I I3 of the nut I I2 nested in opposed notches |I4 in theportions IIB and 55 III of the carriage I9. The carriage may be placedin engagement with the travelling nut I2, as just described, when thenut II2 is in its extreme right hand position and when the beam 61 isheid in its upper inoperative position by the eccentric !4. The specimensupporting carriage |l. thus having been placed in the apparatus with aspecimen positioned thereon, switch |40 may be closed to supply currentto the various electrically .operated portions of the apparatus and toprepare the apparatus for operation, whereupon switch I 46 may beclosedmomentarily to initiate a testing operation, it being assumed thatthe probe B4 is in either its operative or in its inoperm ative positionand is locked therein so that eitherl a mar resistance or scratchadhesion test may be performed and it also being assumed that the properweights 1t have been placed upon the weight-supporting carriage 23. Withthe appa- 7;, ratus thus conditioned for operation, the switch A I maybe operated to advance the carriage I9 to the position shown in Fig. 1,whereupon the beam 91 may be lowered to engage the probe with thecoating III on the sheet of metal III) comprising the test specimen. Asthe carriage I9 moves to the left from the position shown in Fig. 1through the action of the travelling nut I I2 and the drive screw 21,the carriage 29 will move to the right due to the cooperation betweenthe drive screw 28 and the travelling nut 13, thus gradually increasingthe load applied to the probe bearing on the test specimen. The carriageI9 will continue to move to the left until it engages the switch |41 torelease the locking circuit for relay |42 or until the probe breaksthrough the coating on the test specimen and, through the amplifier |50,energizes relay |48 to stop the operation of the apparatus. If the probedoes not break through the coating, the handle 96 may be manipulated todisengage the probes from the test Aspecimen by lifting the right end ofthe beam 61, and reversing switch |49 may be momentarily operated tointerrupt current to relay |42 and supply current to relay |43, tosupply a current in a reverse direction through the leads |45 and thusreverse the direction of drive of the motor I1. The motor I1 willcontinue to drive`the carriage I9 to the right and the carriage 29 tothe left until the carriage I9 engages and operates switch |54 to breakthe locking circuit to the relay |43. 'I'he carriage thus being returnedtoits right hand or inoperative position, it may be picked up off thetravelling nut II2 and reengaged therewith with the projections |I3engaging the next set of notches I I4 and more weight may be placed uponthe carriage 29 and the test specimen may then be retested with moreweight on the weight-supporting carriage 29. These testing operationsmay be repeated, adding more weight to the carriage 29 until the coatingIII on the sheet of metal IIli has been broken, thereby to measure themar resistance or scratch adhesion value of the coating III.Furthermore, by changing the position of carriage I9, a series of testsmay be made on a single test panel to determine the average marresistance or scratch adhesion over .different portions of its surface.

It should be noted that each time a circuit is completed to the motorI1, a circuit is completed in parallel to the solenoid I6 to release thebrake member 41 from the brake band 4B and that each time the circuit tothe motor I1 is broken, solenoid I6 will be deenergized to quickly stopany overrun of the feed screws, whereby the position of the referenceline |08 on the weight supporting carriage 29 will give an accurateindication of the amount of weight required to break through the coatingwith the probe and thereby indicate either the mar resistance or scratchadhesion value of the coating III, depending upon which probe is beingused.

What is claimed is:

1. In an apparatus for testing a coating on a test panel, a supportingframework having a flat supporting surface, a rotatable threaded driveshaft longitudinally mounted on said framework in parallel relation tosaid fiat supporting surface, a nut operatively engaging said threadeddrive shaft and slidably engaging said framework for longitudinalmovement thereon, a test panel supporting carriage mounted for movementon the supporting surface of said framework, an elongated transverselydisposed recess in said carriage having wall portions slidablyengageable with portions of said nut, a plurality of vertical slots 8formed in one of'said wall portions of said carriage, a projection onsaid nut slidably engageable in said vertical slots, the arrangement ofthe nut and the carriage being such that the carriage may be verticallyapplied and connected to said nut in a plurality of lPositionstransversely of the movement of the"n`ut for longitudinal movementtherewith, means on said carriage for clamping said panel thereto, atest probe engageable with the coating of a panel on said carriage, andmeans operable in timed relation to the rotation of said drive shaft forincreasing the pressure of said probe on said coating.

2. In an apparatus for testing a coating on a test panel, a supportingframework having a supporting surface, a rotatable threaded drive shaftlongitudinally mounted on said framework in parallel relation to saidsurface, a nut operatively engaging said threaded drive shaft andslidably engaging said framework for longitudinal movement thereon, atest panel supporting carriage supported for movement on the supportingsurface of said framework, an elongated transversely disposed recess insaid carriage having wall portions slidably engageable with portions ofsaid nut, a plurality of vertical slots formed in one of said wallportions of said carriage, 9, projection on said nut slidably engageablein said vertical slots, the arrangement of the nut and the carriagebeing such that the carriage may be vertically applied and connected tosaid nut in a plurality of positions transversely of the movement of thenut for longitudinal movement therewith, a test probe engageable withthe coating of a panel on said carriage, a, beam pivoted on saidframework and extending longitudinally thereof for supporting said testprobe, a weight supportingcarriage movable along said beam, a secondrotatable threaded drive shaft longitudinally mounted on said frameworkin spaced relation to said beam, a nut operatively engaging said seconddrive shaft for longitudinal movement thereon, a channel member mountedon said framework adjacent and in parallel relation to said second driveshaft and engageable with the nut thereon to prevent its rotation. saidweight supporting carriage having portions vertically slidablyengageable with the nut on said second drive shaft for connecting saidcarriage to saidnut for longitudinal movement therewith, and means forsimultaneously driving said drive shafts.

3. In an apparatus for testing a coating on a A test panel, a supportingframework having a supporting surface thereon, a rotatable threadeddrive shaft longitudinally mounted on said framework parallel to saidsupporting surface. a nut operatively engaging said drive shaft andslidably engaging said framework for longitudinal movement thereon, atest panel supporting carriage supported for movement on the supportingsurface of said framework, said carriage being recessed to receive aportion of said nut therein to establish a driving connection with saidnut for longitudinal movement therewith, a test probe for engaging thecoating of a panel on said carriage, a beam pivoted on said frameworkand extendmg longitudinally thereof for supporting said test probe, aweight-supporting carriage movable along said beam, a second rotatablethreaded drive shaft longitudinally mountedin said framework in spacedrelation to said beam, a nut operatively engaging said second driveshaft for longitudinal movement thereon, a channel member mounted onsaid framework in parallel relation to said second drive shaft andengageable with the nut thereon to prevent its rotation, said weightsupporting carriage having portions vertically slidably engageable withsaid nut for connecting said carriage to said nut for longitudinalmovement therewith, and a power drive for simultaneously driving saiddrive shafts.

4. In an apparatus for testing a coating on a test panel, a supportingframework having a supporting surface and a pair of upwardly extendingend walls, a pair of rotatable threaded drive shafts journalled oneabove the other in said walls in spaced and parallel relation to thesupporting surface of said framework and with the lowermost shaftadjacent thereto, a nut operatively engaging said lowermost drive shaftfor longitudinal movement thereon and slidingly engaging the supportingsurface of said framework, a nut operatively engaging the upper driveshaft for longitudinal movement thereon, a channel member mounted onsaid walls in spaced and parallel relation to said upper drive shaft andengageable with said nut for preventing the rotation thereof, a beampivotally mounted on said framework and extending longitudinally thereofadjacent said upper drive shaft, a test panel carriage supported formovement on said flat supporting surface of said framework andengageable with the nut on said lower drive shaft for longitudinal,movement therewith, a test probe mounted on said beam and engageablewith the coating of a panel on said panel carriage, a weight supportingcarriage movable longitudinally on said beam and vertically slidablyengageable with the nut to establish a, connection therewith forlongitudinal movement with said nut, drive means for simultaneouslyrotating said drive shafts, and a cam member mounted on said wall andengageable with the end of said beam for moving the end thereof to raisethe probe from the panel.

5. In an apparatus for testing a coating on a test panel, a supportingframework having a straight supporting surface and a pair of uprightframe elements, a pair of rotatable threaded drive shafts journalled oneabove the other in said frame elements in spaced and parallel relationto the supporting surface of said framework and with the lowermost shaftadJacent thereto, a

10 nut operatively engaging said lowermost drive shaft for longitudinalmovement thereon and slidably engaging the supporting surface of saidframework,` a nut operatively engaging the upper drive shaft forlongitudinal movement thereon, a member mounted on said frame elementsin spaced and parallel relation to said upper drive shaft and engageablewith said nut for preventing the rotation thereof, a beam pivotallymounted on said framework and extending longitudinally thereof adjacentsaid upper drive shaft, a test panel carriage mounted for movement onthe supporting surface of said framework and engageable with the nut onthe lower drive shaft for longitudinal movement therewith, meansincluding cooperating portions on said test carriage and the nut on saidlower drive shaft for laterally adjustably connecting said test carriageto said nut for longitudinal movement therewith, a test probe mounted onsaid beam and engageable with the coating on a panel on said panelcarriage, a weight supporting carriage movable longitudinally on saidbeam and vertically slldably engageable with the nut on the upper driveshaft to establish a connection therewith fo'r longitudinal movementwith said nut, drive means for simultaneously rotating said shafts, andmeans mounted on one of said frame elements operable to tilt said beamto raise the probe from the panel.

JEROME R. MARCUS.

REFERENCES CITED The following references areof record in the le of thispatent:

Germany Sept. 9, 1929

